1,166 research outputs found

    Virtual image out-the-window display system study. Volume 2 - Appendix

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    Virtual image out-the-window display system imaging techniques and simulation devices - appendices containing background materia

    Future Foam

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    We study pocket universes which have zero cosmological constant and non-trivial boundary topology. These arise from bubble collisions in eternal inflation. Using a simplified dust model of collisions we find that boundaries of any genus can occur. Using a radiation shell model we perform analytic studies in the thin wall limit to show the existence of geometries with a single toroidal boundary. We give plausibility arguments that higher genus boundaries can also occur. In geometries with one boundary of any genus a timelike observer can see the entire boundary. Geometries with multiple disconnected boundaries can also occur. In the spherical case with two boundaries the boundaries are separated by a horizon. Our results suggest that the holographic dual description for eternal inflation, proposed by Freivogel, Sekino, Susskind and Yeh, should include summation over the genus of the base space of the dual conformal field theory. We point out peculiarities of this genus expansion compared to the string perturbation series.Comment: 23 pages, 6 figure

    Dietary Analysis of Batfishes (Lophiiformes: Ogcocephalidae) in the Gulf of Mexico

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    Stomach content analyses, performed on three species of batfishes, Halieutichthys aculeatus, Ogcocephalus declivirostris, and Ogcocephalus pantosticus collected in the Gulf of Mexico in summer (June-July) and fall (Oct.-Nov.) 2002 and 2003, revealed a variety of benthic invertebrates, particularly gastropods, polychaete worms, and xanthid crabs. Schoener\u27s dietary overlap indices (Sl) were calculated between the three species within the same seasons, and within each species between seasons. SI values indicated that each species consumed a different assemblage of prey and that two of the species exhibited temporal variation in diet

    Canonical Demon Monte Carlo Renormalization Group

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    We describe a new method to compute renormalized coupling constants in a Monte Carlo renormalization group calculation. The method can be used for a general class of models, e.g., lattice spin or gauge models. The basic idea is to simulate a joint system of block spins and canonical demons. In contrast to the Microcanonical Renormalization Group invented by Creutz et al. our method does not suffer from systematical errors stemming from a simultaneous use of two different ensembles. We present numerical results for the O(3)O(3) nonlinear σ\sigma-model.Comment: LaTeX file, 7 pages, preprints CERN TH.7330/94, MS-TPI-

    A note on spherically symmetric naked singularities in general dimension

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    We discuss generalizations of the recent theorem by Dafermos (hep-th/0403033) forbidding a certain class of naked singularities in the spherical collapse of a scalar field. Employing techniques similar to the ones Dafermos used, we consider extending the theorem (1) to higher dimensions, (2) by including more general matter represented by a stress-energy tensor satisfying certain assumptions, and (3) by replacing the spherical geometry by a toroidal or higher genus (locally hyperbolic) one. We show that the extension to higher dimensions and a more general topology is straightforward; on the other hand, replacing the scalar field by a more general matter content forces us to shrink the class of naked singularities we are able to exclude. We then show that the most common matter theories (scalar field interacting with a non-abelian gauge field and a perfect fluid satisfying certain conditions) obey the assumptions of our weaker theorem, and we end by commenting on the applicability of our results to the five-dimensional AdS scenarii considered recently in the literature.Comment: 16 pages, no figures, typos fixe

    DNA methylation profiling to assess pathogenicity of BRCA1 unclassified variants in breast cancer

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    Germline pathogenic mutations in BRCA1 increase risk of developing breast cancer. Screening for mutations in BRCA1 frequently identifies sequence variants of unknown pathogenicity and recent work has aimed to develop methods for determining pathogenicity. We previously observed that tumor DNA methylation can differentiate BRCA1-mutated from BRCA1-wild type tumors. We hypothesized that we could predict pathogenicity of variants based on DNA methylation profiles of tumors that had arisen in carriers of unclassified variants. We selected 150 FFPE breast tumor DNA samples [47 BRCA1 pathogenic mutation carriers, 65 BRCAx (BRCA1-wild type), 38 BRCA1 test variants] and analyzed a subset (n=54) using the Illumina 450K methylation platform, using the remaining samples for bisulphite pyrosequencing validation. Three validated markers (BACH2, C8orf31, and LOC654342) were combined with sequence bioinformatics in a model to predict pathogenicity of 27 variants (independent test set). Predictions were compared with standard multifactorial likelihood analysis. Prediction was consistent for c.5194-12G>A (IVS 19-12 G>A) (P>0.99); 13 variants were considered not pathogenic or likely not pathogenic using both approaches. We conclude that tumor DNA methylation data alone has potential to be used in prediction of BRCA1 variant pathogenicity but is not independent of estrogen receptor status and grade, which are used in current multifactorial models to predict pathogenicity

    Onshore Transport of Elopomorph Leptocephali and Glass Eels (Pisces: Osteichthyes) in the Florida Keys

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    The influx of elopomorph leptocephali and glass eels to Florida Bay was monitored on 160 nights from January through December 1993. Metamorphic leptocephali and glass eels were both captured in channel nets moored in Channel Five near Long Key, FL. Eighty-eight percent of the 2,811 leptocephali collected were speckled worm eels (Myrophis punctatus, n = 2,486). The remaining 12% of leptocephali consisted of nine species, including key worm eels (Ahlia egmontis, n = 153), shrimp eels (Ophichthus gomesi, n = 69), and moray eels (Gymnothorax spp., n = 33). The glass eels collected were Myrophis punctatus (n = 230) and Ahlia egmontis (n = 34). Recruitment of leptocephali and glass eels into Florida Bay was seasonal. Myrophis punctatus leptocephali recruited into Florida Bay during fall and winter and were most abundant during November-January. Peak periods of recruitment were associated with nighttime moonless flood tides, strong onshore winds, and easterly (along-shelf) winds. Ahlia egmontis leptocephali recruited during January-April. Ophichthus gomesi was the only species with major recruitment during the summer and fall (July-November). All of the glass eels were captured from January to April

    Analytic Study for the String Theory Landscapes via Matrix Models

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    We demonstrate a first-principle analysis of the string theory landscapes in the framework of non-critical string/matrix models. In particular, we discuss non-perturbative instability, decay rate and the true vacuum of perturbative string theories. As a simple example, we argue that the perturbative string vacuum of pure gravity is stable; but that of Yang-Lee edge singularity is inescapably a false vacuum. Surprisingly, most of perturbative minimal string vacua are unstable, and their true vacuum mostly does not suffer from non-perturbative ambiguity. Importantly, we observe that the instability of these tachyon-less closed string theories is caused by ghost D-instantons (or ghost ZZ-branes), the existence of which is determined only by non-perturbative completion of string theory.Comment: v1: 5 pages, 2 figures; v2: references and footnote added; v3: 7 pages, 4 figures, organization changed, explanations expanded, references added, reconstruction program from arbitrary spectral curves shown explicitl

    Optimal Resource Allocation in Random Networks with Transportation Bandwidths

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    We apply statistical physics to study the task of resource allocation in random sparse networks with limited bandwidths for the transportation of resources along the links. Useful algorithms are obtained from recursive relations. Bottlenecks emerge when the bandwidths are small, causing an increase in the fraction of idle links. For a given total bandwidth per node, the efficiency of allocation increases with the network connectivity. In the high connectivity limit, we find a phase transition at a critical bandwidth, above which clusters of balanced nodes appear, characterised by a profile of homogenized resource allocation similar to the Maxwell's construction.Comment: 28 pages, 11 figure
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